PROJECT SUMMARY Human Tissue Chips that accurately mimic organ-level structure and function are essential building blocks for fully functional Human Microphysiological Systems (MPS) to recreate complex system-level interactions between various organs and tissues. Human MPS have great potential to revolutionize basic and translational research and provide platforms for drug testing and disease modeling with direct relevance to humans. Cardiac Tissue Chips are of particular importance as they can not only be used to model cardiovascular disease but also represent an essential component of any MPS platform used for drug discovery as drug induced cardiotoxicity (arrhythmia risk) is a major reason for pharmaceutical withdrawal of FDA approved drugs. Development of physiologically relevant models of the human myocardium is challenging due to the lack of appropriate human cell types and culture systems. Recent breakthroughs in stem cell research have resulted in human induced pluripotent stem cell derived cardiomyocytes (hiPS-CM) but these cells are immature in phenotype and differ from human adult cardiomyocytes in terms of electrophysiological function, calcium handling, metabolism, and contractile function. The heart is a dynamic organ responsible for maintaining systemic circulation and platforms to culture engineered tissue need to recreate pressure-volume changes associated with physiological or pathophysiological heart (pump) function. To address shortcomings with current Cardiac Tissue Chip platforms, we developed a biomimetic cardiac tissue model (BCTM) that can subject engineered 3D cardiac tissue to pressure-volume changes associated with the ventricular chamber. Using the BCTM, we generated new data that demonstrates our ability to: (1) recreate pressure-volume changes associated with embryonic heart development to accomplish early maturation of hiPS-CMs and (2) recreate pathological tissue remodeling associated with pressure and volume overload. To establish the BCTM as a powerful Cardiac Tissue Chip Model that can either be used independently as a model of cardiovascular development and disease, or integrated within MPS for drug discovery and testing, we hypothesize: ?Establishment of physiologically relevant Human Cardiac Tissue Chip Models that can replicate in vivo ?like structural remodeling and functional adaptation as seen during heart development, normal function, and disease requires culture of engineered cardiac tissue under pressure-volume changes associated with each of these conditions?. To test this hypothesis, we propose three independent aims that focus on differentiation and maturation of hiPS- CMs as a model of congenital heart disease, device-based approach to mitigate pathological cardiac tissue remodeling and evaluate the cardiomyocyte circadian clock in development and disease. Successful completion of this project will validate the BCTM as a relevant model of the human ventricle for cardiovascular disease modeling and for potential integration with MPS platforms.